Method of terminating a resistor



March 5, 1968 J, R. O'KEEFFE 3,371,412

METHOD OF TERMINATING A RESISTOR Filed Feb. 11, 196e INVENTOR. f4/#E5 E@Jeff/FFE BY @MWC/@ffm 3,371,412 METHOD F TERMHNATING A RESISTOR JamesR. GKcelie, Columbus, Nebr., assignor to Dale Electronics, Inc.,Columbus, Nebr., a corporation of Nebraska Filed' Feb. 11, 1966, Ser.No. 526,898 8 Claims. (Cl. 29-621) This invention relates to a resistorand more particularly to a resistor of the continuous wound type and themethod of making the same. This invention also relates to resistorswherein the resistance means is comprised of deposited carbon, metalfilm or the like.

Resistors of the type disclosed herein consist generally of a coreoverwound with resistance wire and terminals electrically connected tothe resistance wire at opposite ends of the core. The problem that theresistor industry is facing is to develop a satisfactory method ofterminating the continuous wound resistors which provides goodmechanical strength and electrical contact between the terminals and theresistance wire and which does not allow the resistance wire to shift onthe core or to protrude from the end of the resistor. Several differentmethods of termination have been attempted but all have proved to beexpensive and unreliable to various degrees. One method used heretoforewas to weld the lead wire to the terminal. A second method usedheretofore was to insert the lead wire through slits formed in theterminal. A third method used heretofore was to pinch the lead wirebetween the ends of the terminal stock. These three methods require thatthe fiber glass or the like core overwound with resistance wire be cutto length prior to the attachment of the terminal. When so cut, the coreand resistance Wire unravel thereby causing shorted turns, poorelectrical contact, poor mechanical strength, and resistance wireprotruding from the terminals. Certain of the manufacturers of resistorshave attempted to solve the unraveling problem by several methodsincluding core impregnants, insulated wire, etc. These remedial methodshave also been generally unsuccessful due to their expense andunreliability.

Therefore, it is a principal object of this invention to provide aresistor wherein the core and the resistance wire do not becomeunravelled during the manufacture thereof.

A further object of this invention is to provide a resistor having a berglass core and resistance wire overwound thereon which does not becomeunravelled during the manufacture thereof.

A further object of this invention is to provide a resistor wherein theresistance wire does not objectionably protrude from the resistor.

A further object of this invention is to provide a resistor which hasgood electrical contact between the resistance wire and the terminals.

A further object of this invention is to provide a resistor which hasgood electrical contact between the terinals and the lead wires.

A further object of this invention is to provide a resistor which hasexcellent mechanical strength.

A further object of this invention is to provide a method of making aresistor wherein the terminals are attached i thereto before the core iscut to length.

A further object of this invention is to provide a machine processmethod of making a resistor which does not require core impregnation orother similar methods of adhering the resistance wire to the core.

A further object of this invention is to provide a method of making aresistor which provides two terminations per machine cycle.

A further object of this invention is to provide a method nited StatesPatent of making a resistor which eliminates a secondary operation to'bond the lead wire to the terminal.

A further object of this invention is to provide a resistor which iseconomical of manufacture, durable in use and refined in appearance.

These and other object will be apparent to those skilled in the art.

This invention consists in the construction, arrangements, andcombination of the various parts ofthe device, whereby the objectscontemplated arev attained as hereinafter more fully set forth,specically pointed out in the claims, and illustrated in theaccompanying drawings in which:

FIG. l is a side view of the resistor with a portion thereof cut away tomore illustrate the invention;

FIG. 2 is end view of the resistor of FIG. 1;

FIG. 3 illustrates one of the initial steps in the method of making theresistor wherein the wound core and lead wire are fed into the machinein parallel paths and the terminal stock is fed perpendicularly to thelead wire;

FIG. 4 illustrates the components of the resistor after the terminalstock has been cut and crimped around the lead wire and core;

FIG. 5 illustrates the components of the resistor after the assembly hasbeen cut through the middle of the terminal to form two assemblies;

FIG. 6 illustrates the ends of the two assemblies formed illustratingthe manner in which the lead wire has been bent back over the terminal;

FIG. 7 illustrates one of the initial steps in a modified method ofmaking the resistance wire wherein the lead wire has vbeen wrappedaround the core; and

FIG. 8 illustrates the components of the resistor of FIG. 7 after theassembly has been cut through the middle of the wrapped lead wire andthrough the core to form two assemblies.

FIG. 9 is a sectional view of a bimetallic terminal stock material whichmay be substituted for the terminal stock material of FIGS. 1-6.

The resistor of FIG. l is referred to by the reference numeral 10 whilethe resistor of FIG. 8 is generally referred to by the reference numeral11.

Resistor 1li is constructed by feeding an elongated core material 12 offiber glass or the like having a resistance wire 14 overwound thereoninto a machine 16. As seen in FIG. 3, machine 16 includes spaced apartmembers 18 and 2t). An elongated lead wire material 22 of copper or thelike is fed into machine 16 parallel to core material 12 and is spacedtherefrom and an elongated strip of terminal stock 24 is fed intomachine 16 transversely to core material 12 and lead wire material 22.Core material 12, lead wire material 22 and terminal stock 24 are fedinto machine 16 simultaneously and the relationship between thesecomponents at this time is illustrated in FIG. 3. Terminal stock 24 maybe comprised of a bimetallic terminal stock material 40 such as seen inFIG. 9 if desired. Terminal stock 40 is provided with a brazeable layer42 comprised of silver solder or the like laminated onto a brass or likelayer 44.

The next step in the manufacture of resistor 10 is illustrated in FIG.4. The terminal stock 24 is cut to the proper length and crimped aroundthe lead wire material 22 and core material 12 -by any suitable means.The crimping of terminal stock 24 around lead wire material 22 and corematerial 12 causes lead wire material 22 and terminal stock 24 to bemoved towards core material 12 at a point between members 18 and 20 ofmachine 16 thereby causing lead wire material 22 to -be bent asillustrated in FIG. 4. If terminal stock 49 is used rather than terminalstock 24, the terminal stock would be heated in a secondary operationthereby fusing or brazing layer 42 into intimate contact with theresistance wire.

The next step in the manufacture of resistor 10 is illustrated in FIG.5. The assembly is cut through the middle of terminal stock 24transversely to the longitudinal axis of core material 12 |by anyconvenient means thereby forming opposite ends of two resistors 10.Machine 16 would normally be adapted so that the other ends of the tworesistors 10 would be terminated simultaneously with the termination ofthe ends shown and described. FIG. 6 illustrtaes the manner in which thelead wire material 22 is bent back over the terminals of the tworesistors 10.

The completed resistor 10 is shown in FIG. 1 and includes a core 12Aoverwound with resistance wire 14A. A terminal 24A is provided at oneend of resistor 10 and a terminal 24B is provided at the other end ofresistor 10. A lead wire 22A is operatively electrically connected toterminal 24A as previously described and includes a U-shaped end portion26A embracing the interior surface, the inner end and exterior surfaceof terminal 24A. Lead wire 22A also includes an L-shaped portion 28Awhich at rst extends downwardly and thence outwardly with respect to endportion 26A and terminal 24A as seen in FIG. l.

Terminal 24B is identical to terminal 24A and for that reason will notbe described in detail. A lead wire 22B, identical to lead Wire 22A, iselectrically connected to terminal 24B as previously described. Resistor10 may be coated with any suitable material if desired.

With respect to FIGS. 7 and S, the numeral 30 generally designates acore material overwound with resistance wire 32. A lead wire material 34is simply wrapped around core 30 as illustrated in FIG. 7. The assemblyis then cut through the middle of the wrapped lead wire material (FIG.8) by any suitable means. The cutting of the assembly results in theopposite ends of two resistors 11 being formed wherein the wrapped leadWire material serves as both a lead wire and a terminal. Normally, thetermination of the opposite ends of the two resistors 11 would beaccomplished at the same time as the termination of the ends shown inFIG. 8. In FIG. 8, the terminal assembly at the right end of the leftresistor 11 is referred to as 34A and the terminal assembly at the leftend of the right resistor 11 is referred to as 34B.

The advantages of the resistor 10 are as follows: 1) the inventionallows machine processes which do not require'core im-pregnation or someother method o'f adhering the resistance wire to the core; (2) a doubleWidth terminal stock is used which is sliced in two thereby giving twoterminations per machine cycle; (3) the slicing operation occurs aftertermination thus eliminating frayed ends or resistance wire protrudingfrom'the terminals; (4) mechanical strength of the resistor is increasedbecause stress imposed on the lead wire acts against the bend thereofand not on the joint; the resistor is economically manufactured since asecondary operation is not required to Abond the terminal to the leadwire; and (6) mechanical strength and electrical contact are furtherimproved byuse of a fusible or`brazeable terminal stock (example: silversolder laminated to brass), which when heated in a secondary operationprovides intimate contact with the resistance wire.

The advantages of the resistorll are as follows: (l) the Wrapped leadwire serves as both a terminal and a lead wire; and (2) superiormechanical strength and electrical contact are realized, and furtherimproved by use of fusable lead wire which when heated in a secondaryoperation provides intimate contact with the resistance wire. While theresistor has been described as including a resistance wire overwound ona core, a resistor without a resistance wire can beproduced by themethod described herein. Such resistors would substitute depositedcarbon or, a metal iilm or the like for the resistance wire.

It should be noted that the resistor core can be of -any configurationand has been shown to be cylindrical in the drawings for sake ofsimplicity.

Thus it can be seen that the device and he method of making the sameaccomplishes at least all of the stated objectives.

Some changes may be made in the construction and arrangement of mymethod of terminating a resistor without departing from the real spiritand purpose of my invention, and it is my intention to cover by myclaims, any modiiied forms of structure or use of mechanical equivalentswhich may be reasonably included within their scope.

I claim: 1. The method of making a resistor, comprising the followingsteps:

securing a terminal stock material around an elongated core and a lengthof lead wire material, said core and lead wire being parallel, said corehaving resistance wire means operatively overwound thereon, said leadwire being positioned between the resistance Wire and the terminal stockmaterial,

cutting said terminal stock material, said lead wire and said core atthe approximate center width of said terminal stock materialtransversely to the longitudinal axis of said core thereby foaming oneend of two resistors.

2. The method of claim 1 wherein the other end of one of the resistorsis formed by securing a second terminal stock material around said oneresistor core and around a second length of lead wire material, saidcore and said second length of lead Wire material being parallel, saidsecond lead wire being positioned between the resistance wire and saidsecond terminal stock material, and cutting said second terminal stockmaterial, said second lead wire and said core at the approximate centerwidth of said second terminal stock material transversely to thelongitudinal axis of said core.

3. A method of terminating resistors comprising the steps of: providinga length of core material with resistance material thereon, providing alength of lead wire, providing a terminal band, securing said lead wireto said resistance material by wra-pping said terminal band around saidcore, said lead wire being between said band and said resistancematerial and having lengths thereof extending from both sides of saidterminal band; severing said terminal band, said lead wire and said corein a direction substantially transverse to the longitudinal axis of saidcore.

4. The method of claim 3 wherein said securing includes the step offusing said lead wire, terminal band and resistance material with afusible material.

5. The method of claim 3 wherein said severing is ap- `proximatelyin'the center of said terminal band.

6. A method of terminating resistor comprising the steps of: providing alength of core material with resistance material thereon, providing alength of lead wire, securing said lead wire to said resistance materialby wrapping a plurality of turns circumferentially around said coreleaving a length of said lead wire at both ends of the wrapped section;severing said lead wire and said core through the wrapped portion ofsaid lead wire.

7. The method of claim 6 wherein said securing includes the step offusing said wrapped portion of said lead wire to said resistancematerial with a fusible material.

8. The method of claim 6 wherein said severing is approximately at theIcenter of said wrapped portion.

References Cited UNITED STATES PATENTS 1,745,939 2/1930 Loewe 338-308 X2,113,674 4/1938 Brickman et al. 29-621 2,357,473 9/1944 Iira 338-308 X2,402,122 6/1946 'Bollinger 338-322 X 2,489,409 11/1949 Green et al.338-322 X 2,645,701 7/1953 Kerridge et al. 338-308 X 2,966,649 12/1960Haynman 338-322 JOHN F. CAMPBELL, Primary Examiner.

'1. L.`CLINE, Assistant Examiner.

3. A METHOD OF TERMINATING RESISTORS COMPRISING THE STEPS OF: PROVIDINGA LENGTH OF CORE MATERIAL WITH RESISTANCE MATERIAL THEREON, PROVIDING ALENGTH OF LEAD WIRE, PROVIDING A TERMINAL BAND, SECURING SAID LEAD WIRETO SAID RESISTANCE MATERIAL BY WRAPPING SAID TERMINAL BAND AROUND SAIDCORE, SAID LEAD WIRE BEING BETWEEN SAID BAND AND SAID RESISTANCEMATERIAL AND HAVING LENGTHS THEREOF EXTENDING FROM BOTH SIDES OF SAIDTERMINAL BAND; SEVERING SAID TERMINAL BAND, SAID LEAD WIRE AND SAID COREIN A DIRECTION SUBSTANTIALLY TRANSVERSE TO THE LONGITUDINAL AXIS OF SAIDCORE.
 6. A METHOD OF TERMINATING RESISTOR COMPRISING THE STEPS OF :PROVIDING A LENGTH OF CORE MATERIAL WITH RESISTANCE MATERIAL THEREON,PROVIDING A LENGTH OF LEAD WIRE, SECURING SAID LEAD WIRE TO SAIDRESISTANCE MATERIAL BY WRAPPING A PLURALITY OF TURNS CIRCUMFERENTIALLYAROUND SAID CORE LEAVING A LENGTH OF SAID LEAD WIRE AT BOTH ENDS OF THEWRAPPER SECTION; SEVERING SAID LEAD WIRE AND SAID CORE THROUGH THEWRAPPED PORTION OF SAID LEAS WIRE.